A main portion of a conventional reclining apparatus of a seat for a vehicle of this kind will be described with reference to FIGS. 1 and 2.
In FIG. 1, an arm 3a is disposed in a rear side portion of a base plate 1 and is fixed to an upper teeth section 3 having a latch gear 2 at the lower edge thereof, and is pivotally mounted to a shaft 4. The arm 3a is biased by an unillustrated spring in the direction of arrow 5. A lower portion of an unillustrated back arm is fixed to the arm 3a . A holder plate 6 disposed outside the upper teeth section 3 is fixed to shafts 4, 7 and 8 respectively fixed to the base plate 1. A lower teeth section 9 is disposed between the holder plate 6 and the base plate 1, and is biased in the counterclockwise direction in FIG. 3 by an unillustrated spring pivotally attached to the shaft 8 in a base portion thereof. A teeth portion 9a formed at a free end of the lower teeth section 9 is engaged with and disengaged from the latch gear 2 by a roller described later to lock and unlock the back arm fixed to the arm 3a.
An operating lever 11 and a roller 12 mounted outside the operating lever 11 are respectively pivotally mounted to the shaft 7. The operating lever 11 is biased in the direction of arrow 14 by a compression spring 13 engaged with the base plate 1 and the operating lever 11 at both ends thereof. The teeth portion 9a of the lower teeth section 9 and a side edge 9b thereof opposite the teeth portion 9a press and contact the roller 12. The teeth portion 9a of the lower teeth section 9 presses and contacts the latch gear 2 of the upper teeth section 3 by the biasing force of the compression spring 13 acting on the operating lever 11, thereby locking the upper teeth section 3 and the back arm integral therewith.
As shown in FIG. 2, a pin 16 fixed to the lower teeth section 9 extends through an elongated hole 15 disposed in the base plate 1. When the distance between the pin 16 and a side edge of the elongated hole 15 is a predetermined length, the teeth portion 9a of the lower teeth section is completely locked by the latch gear 2 of the upper teeth section 3. An attaching portion 17 is formed in a suitable portion of the holder plate 6 by bending a free end thereof to attach a rear portion of an unillustrated finisher cover for closing a side face of the base plate 1. A bent piece 18 is disposed in a suitable portion of the holder plate 6 on an upper edge side thereof to prevent dust from entering an engaging portion of the upper teeth section 3 and the lower teeth section 9.
In the reclining apparatus of a seat for a vehicle, it is checked in an assembly process whether the lower teeth section 9 and the latch gear 2 of the upper teeth section 3 are reliably locked or not. For example, there is a case in which the teeth portion 9a of the lower teeth section 9 is not reliably locked by the latch gear 2 of the upper teeth section 3 by errors in processing state and accuracy, etc. of the respective parts constituting the reclining apparatus, so that the teeth portion 9a is separated from the latch gear.
In the conventional reclining apparatus mentioned above, to check whether the lower teeth section 9 is incompletely locked or not, a clearance gauge is inserted into a clearance formed between the pin 16 of the lever 11 and a side edge of the elongated hole 15 of the base plate 1 to check whether the length of the clearance is proper or not. Another method for confirming the locking state is performed by measuring the rotatable position of the operating lever 11 manually or mechanically.
In the method in which the locking state of the lower teeth section is checked by a clearance gauge, it is necessary to process the elongated hole 15 and the pin 16 used for only the confirmation of the locking state, and operate the clearance gauge for confirmation. Further, it is difficult to confirm the locking state in the method in which an extension of the lower teeth section 9 is manually measured.
In general, when a seat provided with a reclining apparatus is disposed in the so-called two door or three door type vehicle, a seat back is inclined forwards by the operation thereof on the rear seat side so as not to disturb the front seat's side when a person setting on the rear seat gets into and out of the vehicle, for example. The reclining apparatus of this type is normally of the so-called latch type in which the slanting angle of the seat back is changed at many stages. In the reclining apparatus of the latch type, as shown in FIG. 3, in a base plate 52 fixed to a seat cushion 51, an arm 54 fixed to a seat back 55 is biased by a return spring 57 and is pivotally supported by a rotary shaft 53. An upper teeth section 58 is attached to the arm 54 and has a teeth portion located on the circumference thereof around the rotary shaft 53. A lower teeth section 59 is rotatably supported by the base plate 52 and partially has a teeth portion engaged with the teeth portion of the upper teeth section 58. An operating lever 63 engaged with the lower teeth section 59 to rotate it is pivotally supported and biased by a coil spring 64. To incline the seat back 55 forwards from the rear seat, a pedal 65 is pivotally supported by a shaft 60 in a holder plate 56 for supporting a shaft portion such as a rotary shaft 53 opposite the base plate 52, and the pedal 65 is connected to the operating lever 63 by a link 68. Accordingly, when the pedal 65 is depressed, the operating lever 63 is rotated in association with the pedal and the lower teeth section 59 is thereby rotated, so that the engagement of the lower teeth section 59 and the upper teeth section 58 is released and the upper teeth section 58 is rotated. Accordingly, the arm 54 fixed to the seat back 55 is rotated and inclined forwards by the resilient force of the return spring 57. Thus, the person sitting on the rear seat can independently operate the seat back even when no person sits on the front seat.
However, in accordance with the conventional reclining apparatus in which the seat back is inclined by the stepping operation, the lower teeth section 59 and the pedal 65 are constructed such that they are supported by the same shaft 60 between the base plate 52 and the holder plate 56. Therefore, such a structure has the disadvantages with respect to the mechanically engaging strength of the lower teeth section 59 and the upper teeth section 58, and is different in assembly from the general reclining apparatus since the structure has the pedal and the link. Accordingly, in such a structure, it is not avoidable to branch or separately dispose a line process for assembling the reclining apparatus in which the seat back is inclined by the stepped operation on the way to a line process for assembling the standard reclining apparatus, thereby increasing the cost of the apparatus and making the apparatus expensive.
In another conventional reclining apparatus for a vehicle, a seat back can be inclined in the forward and backward directions to take an easy and most comfortable position of a person sitting on the seat. In such a reclining apparatus, an arm is pivotally mounted to a base plate fixed to a seat cushion and is fixed to the seat back so as to be inclined at a predetermined angle through a reclining operating mechanism attached to the base plate. The reclining operating mechanism is composed of a teeth member integrally joined to the arm or an end thereof, and a ratchet pivotally mounted to the base plate and engagable with and disengagable from the teeth member. An operating lever is disposed to oscillate the latchet and is provided with a cam engagable and disengagable from the latchet and is pivotally mounted to the base plate(see Japanese Laid-Open Utility Model No. 55-51310 and Japanese Published Utility Model No. 62-34840).
It is ideal to dispose the reclining apparatus of this type as a pair on the right and left sides of the seat, but a hinge device is often used on either one of the right and left sides to reduce the cost of the seat apparatus. However, when such a hinge device is substituted for the reclining apparatus on one of the right and left sides and the weight of a person sitting on the seat is applied to the seat back by inertia due to the increase in vehicle speed, etc., the seat back is twisted on the side of the hinge device, thereby providing an uncomfortably sitting feeling to the person.
To solve the problems mentioned above, the reclining apparatus has been recently symmetrically disposed on both right and left sides of the seat in many cases. However, when the reclining apparatus is disposed on the right and left sides of the seat in such a way and the seat back is inclined, it is necessary to separately operate right and left operating mechanisms for releasing and locking the engagement of teeth members respectively disposed in the reclining apparatuses, which is a complicated operation. Therefore, the reclining apparatuses have a structure in which one of the right and left mechanisms is moved in association with the other. In such an associating structure, the right and left reclining apparatuses may have the same construction in which shafts of respective operating levers are connected to each other through a shaft so as to drive the apparatuses in association with each other. However, in general, the reclining apparatuses are often driven by a wire in association with each other. In such a structure, the relation between pulling and pulled sides must be provided so that the right and left reclining apparatuses are symmetrically disposed, and are moved in the reverse direction with respect to each other. Otherwise, the right and left reclining apparatuses have the same construction by arranging the wire backwards from a lower portion of the seat cushion.
However, in the structure associated by the wire, when the right and left symmetrical reclining apparatuses are used, it is necessary to dispose two lines of manufacture, increasing the cost of the apparatus. Also, when the right and left reclining apparatuses having the same construction are used and the wire is arranged below a rear portion of the seat cushion, a space for feet of a person sitting on the rear seat becomes small.
When the right and left reclining apparatuses having the same construction are used and the wire is arranged below a front portion of the seat cushion, the relation between the pulling and pulled sides is formed in the right and left reclining apparatuses, as described before. Accordingly, it may be constructed such that, when an operating lever of a main reclining apparatus is rotated to pull the wire, the wire pushes and rotates an operating lever of a driven reclining apparatus. However, it is complicated to press and rotate the operating lever of the driven reclining apparatus by the wire, and the cost is increased and it is also difficult to realize such a structure.
The reclining apparatus is divided into two types, the one for rotating the operating lever manually, and the other for rotating the operating lever by depressing a pedal by a person's foot(see Japanese Laid-Open Utility Model No. 55-51310). Therefore, it is desirable that the structure can be also used in the reclining apparatus of the above step-operating type when the associating structure mentioned above is used.
In general, in a reclining apparatus of a two door type vehicle in which it is necessary to incline the seat back of a front seat forwards when a person sits on the rear seat, hen the seat back is gradually inclined forwards, the seat back can be positioned to a certain degree of the position thereof, but can be freely inclined forwards without the positioning thereof after a certain limited position of the seat back.
FIG. 4 shows a main portion of another conventional reclining apparatus of a seat for a vehicle of this kind.
In FIG. 4, an upper teeth section 103 has a latch gear 103a, and a lower teeth section 112 has a teeth portion 112a engagable with and disengagable from the latch gear 103a. The upper teeth section 103 and the lower teeth section 112 are engaged with each other. The upper teeth section 103 is fixed to a back arm pivotally mounted to a base plate 102 described later and fixing a seat back thereto, and the lower teeth section 112 is pivotally mounted to the base plate 102. A sliding face 103b is formed in a front end portion of the latch gear 103a and rises from an end bottom portion of the latch gear 103a and projects from a teeth tip of the latch gear 103a. A rising face 103d between the sliding face 103b and the bottom portion of the latch gear 103a is formed by extending a side face of the bottom portion.
When the teeth portion 112a of the lower teeth section 112 is disengaged from the latch gear 103a of the upper teeth section 103 by an operating lever 113 described later, the upper teeth section 103 becomes rotatable so that the operating lever 113 returns to the original position thereof by the biasing force of a tension spring 118 described later when an operator separates the operating lever 113 from his hand in a predetermined position, thereby pressing the lower teeth section 112 and engaging the teeth portion 112a with the latch gear 103a again.
When a person sits on the rear seat in the two door type vehicle having the above reclining apparatus and the seat back is inclined forwards excessively, the teeth portion 112a of the lower teeth section 112 contacts the sliding face 103b of the upper teeth section 103 so that the seat back is not positioned. However, when the seat back is raised, the teeth portion 112 of the lower teeth section 112 relatively slides the sliding face 103b. When the teeth portion 112a is disengaged from the sliding face 103b, the teeth portion 112a is automatically engaged with the latch gear 103a by the tension spring 118 biasing the operating lever 113.
However, at this engaging time, the teeth portion 112a of the lower teeth section 112 is located between a teeth face of the latch gear 103a of the upper teeth section 103 and the rising face 103d thereof as shown in FIG. 5, causing a half locking state in which the teeth portion 112a is not completely engaged with the latch gear 103. When such a half locking state occurs, a large load is applied to the seat back when the vehicle is moved first, etc., and the half locking is released, causing a very dangerous state.
To remove the half locking state, a safe reclining apparatus has been proposed in Japanese Laid Open Utility Model No. 59-41154. FIG. 6 shows an engaging state between a latch gear 103a and a teeth portion 112a of a lower teeth section 112. A guide face 103e is disposed in a corner portion of the sliding face 103b and extends from an upper edge of an end bottom portion of the latch gear 103a to the sliding face 103b in the normal direction of a pitch circle of the latch gear 103a. In this embodiment, when the teeth portion 112a is slided on the sliding face 103b and thereafter is engaged with the latch gear 103a and one end of the teeth portion 112a is slided and guided along the guide face 103e, the other end of the teeth portion 112a contacts a teeth tip of the latch gear 103a so that the teeth tip of the other end of the teeth portion 112a can be engaged with the latch gear 103a while sliding and guiding the one end of the teeth portion 112a by the guide face 103e. Therefore, the teeth portion 112a and the latch gear 103a can be engaged with each other without causing the half locking state therebetween.
When the seat back in the sitting state is moved to the forwardly inclined state by the insufficient operation of the operating lever 113, an end portion of the teeth portion 112a of the lower teeth section 112 might not be located outside a moving orbit of the guide face 103e in a certain case. In such a case, the guide face 103e collides with the end portion of the teeth portion 112a by the biasing force of a spiral spring 107 described later, damaging the teeth portion 112a. Further, since the corner portion of the guide face 103e is formed in the shape of an acute angle, the durability of a molding die therefor is low when the upper teeth section 103 is molded.